Metafields are a flexible way for your app to add and store additional information about a Shopify resource, such as a product, a collection, and many other owner types. The additional information stored in metafields can be almost anything related to a resource. Some examples are specifications, size charts, downloadable documents, release dates, images, or part numbers. Merchants and other apps can retrieve and edit the data that's stored in metafields from the Shopify admin. You can also access metafields in themes using Liquid and through the Storefront API.

Metafield definitions enable you to include data validation for metafields, and enable merchants to add metafield values for resources in the Shopify admin. We also provide standard metafield definitions for common use cases. Using standard definitions means that your app can access information that merchants might have already stored in these metafields and provides interoperability across the Shopify platform.

If you don't want metafield data to be accessible to merchants and other apps, then you can use private metafields.